1. Technical Field
The invention relates generally to the reduction of the volume occupied by the components of nuclear fuel assemblies exhausted due to their use in a reactor, for storing same.
Such assemblies generally comprise a bundle of fuel rods and a structure formed of two end pieces connected together by guide tubes and grids spaced apart along the guide tubes and defining rod-retaining pockets.
2. Prior Art
An apparatus has already been proposed in French Pat. No. 2,586,854 for dismantling a fuel assembly by cutting the guide tubes below one of the end pieces, then removing the fuel rods and reducing the volume occupied by the latter by grouping them together in a "bunch" of tightly packed rods.
It is also desirable to reduce the volume occupied by the structure for storing the latter during the required deactivation time.
For that, devices are known for laterally crushing the structure.
A compacting device is also known for use in a dismantling installation, having a compacting chamber whose cross-section is proportioned to that of the assembly, placed vertically, and which is provided with means for introducing the structure and with a jack for longitudinally compacting the structure against a movable member closing one end of the chamber.
The chamber of the device of this type described in French Pat. No. 2,538,939 is provided for receiving and compacting successive sections of the structure, obtained by severing the guide tubes. Each section is crushed in turn against the movable member consisting of a metal slide forming the bottom wall of the compacting chamber. The slide is withdrawn once several sections have been crushed against each other by the jack and the thus compacted structure is collected in a storage container.
That device has drawbacks. Compacting the structure requires numerous successive operations (positioning of the structure, severing it to form a first section, compacting the section, severing and compacting subsequent sections, collection of the compacted structure). The procedure is time consuming. The operations are complex, since the sections other than the first one must be compacted on the section or sections already crushed. Remote control of the device, placed in a water filled pool, is complex. Cutting into sections creates considerable fragments and debris.
There is also known (French Pat. No. 2,600,202) a device for consolidating the fuel rods of an assembly into a bunch for forcing them out of the structure.